irc: support merge operator

Signed-off-by: NotAShelf <raf@notashelf.dev>
Change-Id: Icfb0cc81542e637d4b91c6a5788370fb6a6a6964

src/irc/types.h

@@ -43,7 +43,23 @@ enum class NodeType : uint8_t {
   ERROR = 0xFF
 };
 
-enum class BinaryOp : uint8_t { ADD, SUB, MUL, DIV, CONCAT, EQ, NE, LT, GT, LE, GE, AND, OR, IMPL };
+enum class BinaryOp : uint8_t {
+  ADD,
+  SUB,
+  MUL,
+  DIV,
+  CONCAT,
+  EQ,
+  NE,
+  LT,
+  GT,
+  LE,
+  GE,
+  AND,
+  OR,
+  IMPL,
+  MERGE
+};
 
 enum class UnaryOp : uint8_t { NEG, NOT };
 
@@ -203,11 +219,11 @@ struct ForceNode {
 // Node wraps a variant for type-safe AST
 class Node {
 public:
-  using Variant = std::variant<ConstIntNode, ConstFloatNode, ConstStringNode, ConstPathNode,
-                               ConstBoolNode, ConstNullNode, ConstURINode, VarNode, LambdaNode,
-                               AppNode, BinaryOpNode, UnaryOpNode, AttrsetNode, SelectNode,
-                               HasAttrNode, WithNode, IfNode, LetNode, LetRecNode, AssertNode,
-                               ThunkNode, ForceNode>;
+  using Variant =
+      std::variant<ConstIntNode, ConstFloatNode, ConstStringNode, ConstPathNode, ConstBoolNode,
+                   ConstNullNode, ConstURINode, VarNode, LambdaNode, AppNode, BinaryOpNode,
+                   UnaryOpNode, AttrsetNode, SelectNode, HasAttrNode, WithNode, IfNode, LetNode,
+                   LetRecNode, AssertNode, ThunkNode, ForceNode>;
 
   Variant data;